1. Field of the Invention
The present invention relates to an AD conversion control circuit for inverter controlling a motor.
2. Description of the Related Art
An inverter control device of a brushless motor configured by a microcontroller as one example of a PWM control device is disclosed in Japanese Laid-Open Patent Publication (Japanese Laid-Open Patent Publication No. 2004-357450).
However, in the above conventional inverter control device, a carrier period needs to be reduced and a complex calculation by a CPU is required when configured to perform inverter control of higher accuracy, and thus time necessary for AD conversion tends to become longer. Thus, it is desirable to reduce the time necessary for AD conversion. As a countermeasure therefor, Japanese Laid-Open Patent Publication (Japanese Laid-Open Patent Publication No. 2003-284374) discloses performing two-phase selection control by selecting two out of three phases and calculating the remaining phase from the two selected phases. However, the time necessary for AD conversion becomes longer with such a countermeasure.